Wire rope drive mechanism for reciprocating linear motion

Abstract

A drive mechanism for providing reciprocating, liner motion for a movable work piece relative to a stationary work piece is provided. The drive system includes a motor rotating a drum in forward and reverse directions about a first axis. The motor and drum are fixedly mounted with respect to the stationary work piece, such as to a housing or other structure. The system further includes an elongate, substantially non-flexible cable having a first and second ends fixed with respect to the stationary work piece. The cable further includes an intermediate portion extending between the first and second ends, with the intermediate portion being wound around the drum. First and second bearings are provided which are mounted to the movable work piece. The first bearing is positioned relative to the cable such that the intermediate portion of the cable is wound over the first bearing, and with the first bearing being positioned between the first end of the cable and the drum. The second bearing is positioned relative to the cable such that the intermediate portion of the cable is wound over the second bearing with the second bearing being positioned between the drum and the second end of the cable. Rotation of the drum in either clockwise or counterclockwise directions causes the cable to move the first and second bearings back and forth relative to the drum, thereby causing linear, reciprocating movement of the moveable work piece relative to the stationary work piece.

We claim:  
     
         1 . A drive mechanism for providing reciprocating, liner motion for a movable work piece relative to a stationary work piece, comprising: 
 (a) a motor rotating a drum in forward and reverse directions about a first axis, said motor fixedly mounted with respect to said stationary work piece;    (b) an elongate, substantially non-flexible cable having a first end coupled to said stationary work piece and a second end coupled to said stationary work piece, said cable further comprising an intermediate portion extending between said first and second ends, with said intermediate portion being wound around said drum;    (c) a first bearing coupled to said movable work piece wherein said first bearing is positioned relative to said cable such that said intermediate portion of said cable is wound over said first bearing with said first bearing being positioned between said first end of said cable and said drum; and    (d) a second bearing coupled to said movable work piece wherein said second bearing is positioned relative to said cable such that said intermediate portion of said cable passes is wound over said second bearing with said second bearing being positioned between said drum and said second end of said cable,    (e) wherein rotation of said drum in said forward and reverse directions moves said first and second bearings relative to said drum thereby moving said moveable work piece relative to said stationary work piece and providing reciprocating movement for said moveable work piece.    
     
     
         2 . The drive mechanism of  claim 1 , further comprising a tension spring coupled to said first end of said cable, said tension spring applying a tension to said cable.  
     
     
         3 . The drive mechanism of  claim 1 , wherein said drive mechanism is incorporated into an automated biological sample testing instrument.  
     
     
         4 . The drive mechanism of  claim 1 , wherein said drive mechanism is incorporated into a stacking system for stacking substantially flat and thin card-like objects.  
     
     
         5 . The drive mechanism of  claim 1 , wherein said drive mechanism further comprises: 
 a linear bearing having a first portion fixed with respect to said stationary work piece and defining a direction of linear motion, and a second portion translatable relative to said first portion in a linear fashion in said direction of linear motion; and    said moveable work piece mounted to said second portion of said linear bearing; and    fastening means for fastening said moveable work piece to said second portion of said linear bearing;    wherein rotation of said drum causes said cable to move said moveable work piece in a linear direction defined by said linear bearing.    
     
     
         6 . The mechanism of  claim 1 , wherein said cable comprises a wire rope.  
     
     
         7 . A method of moving a moveable work piece relative to a stationary piece using an elongate, substantially non-flexible cable, said cable having a first end and a second end and an intermediate portion between said first and second ends, comprising the steps: 
 attaching said first and second ends of said cable to a structure fixed with respect to said stationary piece;    winding said intermediate portion of said cable about a drum coupled to a motor, said motor fixed with respect to said stationary piece;    further winding said intermediate portion of said cable around first and second bearings, said first and second bearings coupled to said moveable work piece such that said first bearing is positioned relative to said cable between said first end of said cable and said drum and said second bearing is positioned relative to said cable between said second end of said cable and said drum; and    rotating said drum, whereby said step of rotating causes said first and second bearings to move relative to said drum and thereby move said moveable work piece relative to said stationary work piece.    
     
     
         8 . The method of  claim 7 , wherein said drum rotates about a first axis, and wherein said cable is wound about said first and second bearings such that rotation of said drum about said first axis causes said moveable work piece to move in a linear direction orthogonal to said first axis.  
     
     
         9 . The method of  claim 7 , wherein said moveable work piece reciprocates back and forth along a path, and wherein rotation of said drum in clockwise and counterclockwise directions causes said moveable work piece to move back and forth along said path.  
     
     
         10 . The method of  claim 9 , wherein the method further comprises the steps of: 
 providing an optical sensor in close proximity to said moveable work piece; and    detecting with said optical sensor the position of said moveable work piece relative to said stationary piece to thereby detect when said moveable work piece has reciprocated in said path back to a predetermined position.    
     
     
         11 . The method of  claim 7 , further comprising the step of applying tension to said first end of said cable between said cable and said stationary work piece.  
     
     
         12 . The mechanism of  claim 1 , further comprising an optical sensor placed in registry with a path along which said moveable work piece is moved by said cable, wherein said optical detector senses the position of said moveable work piece relative to said stationary work piece to thereby detect when said moveable work piece has been moved to a predetermined position.  
     
     
         13 . In a stacking system for stacking substantially flat, thin card-like objects in a magazine, said stacking system further comprising a reciprocating member for moving said objects into said magazine, an improved drive mechanism for moving said reciprocating member back and forth in a reciprocating, linear fashion, the improvement comprising: 
 (a) a motor rotating a drum in forward and reverse directions about a first axis, said motor fixedly mounted with respect to said magazine;    (b) an elongate, substantially non-flexible cable having a first end and a second end and an intermediate portion extending between said first and second ends, with said intermediate portion being wound around said drum, said first and second ends attached to fixed structure in said stacking system;    (c) a first bearing coupled to said reciprocating member wherein said first bearing is positioned relative to said cable such that said intermediate portion of said cable is wound over said first bearing with said first bearing being positioned between said first end of said cable and said drum; and    (d) a second bearing coupled to said reciprocating member wherein said second bearing is positioned relative to said cable such that said intermediate portion of said cable passes is wound over said second bearing with said second bearing being positioned between said drum and said second end of said cable,    (e) wherein rotation of said drum in said forward and reverse directions moves said first and second bearings relative to said drum thereby moving said reciprocating member relative to said magazine and providing reciprocating movement for said reciprocating member.    
     
     
         14 . The improvement of  claim 13 , further comprising a spring coupled to said first end of said cable, said tension spring applying a tension to said cable.  
     
     
         15 . The improvement of  claim 13 , wherein said magazine is incorporated into an automated biological sample testing instrument.  
     
     
         16 . The improvement of  claim 13 , wherein said improved drive mechanism further comprises: 
 a linear bearing having a first fixed portion and defining a direction of linear motion, and a second portion translatable relative to said first portion in a linear fashion in said direction of linear motion, said reciprocating member mounted to said second portion of said linear bearing either directly or indirectly;    wherein rotation of said drum causes said cable to move said reciprocating member in a linear manner in said direction of linear motion defined by said linear bearing.    
     
     
         17 . The improvement of  claim 13 , wherein said cable comprises a wire rope.  
     
     
         18 . The improvement of  claim 13 , further comprising an optical sensor placed in registry with a path along which said reciprocating member is moved by said cable, wherein said optical detector senses the position of said reciprocating member to thereby detect when said moveable work piece has been moved to a predetermined position.  
     
     
         19 . The improvement of  claim 17 , wherein said wire rope is coated with a plastic material.  
     
     
         20 . The mechanism of  claim 6 , wherein said wire rope is coated with a plastic material.